Heartbeat Message Fields
| Tag | Field Name | Required | Description |
|---|---|---|---|
| 35 | MsgType | Y | 0 |
| 112 | TestReqID | N | Required in response to a Test Request. |
A Heartbeat message should be sent if the agreed upon HeartbeatInterval has elapsed since the last message sent. If any message has been sent during the preceding HeartbeatInterval a Heartbeat message need not be sent.